Mapping of planation surfaces in the north-central Amazonia

This study aims to identify planation surfaces and their dissected reliefs in the Amazon, starting from the highlands of the border between Brazil, Venezuela and Guiana and ending near the axis of the Amazon River. Its connection with associated surface formations (regoliths) was also evaluated. The input data for the execution of the algorithm used were generated via geoprocessing techniques, which enabled the identification of five planation surfaces: a summit surface, which was associated with the Gondwana surface, from 855 to 2,745 m; a second surface (525–854 m), associated with the Post-Gondwana surface; a third surface, from 279 to 524 m, associated with the South American surface; a fourth surface, from 114 to 278 m, associated with the Velhas I surface (Early Velhas), and a fifth surface, associated with the Velhas II surface (Late Velhas). Thin soils predominate in the first three surfaces, and their presence is attributed to the erosion of the original surface formations with exposure of rock or iron crusts. The two lower surfaces present greater diversity of soils mainly due to the heterogeneity of soil hydrological conditions. In addition to Latossolos (Oxisols) and Argissolos (Ultisols), which are dominant, there are Espodossolos (Spodosols), Plintossolos (Plinthosols), Gleissolos (Gleysols) and Planossolos (Planosols).